The disclosure of Japanese Patent Application No. 2000-309460 filed on Oct. 10, 2000 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a fuel cutoff apparatus mounted in a fuel tank. More particularly, it relates to a float valve apparatus that cuts off communication to a canister to prevent fuel from being sent to the canister when the fuel tank is full.
2. Description of the Related Art
A fuel tank in an automobile is provided with an air intake/exhaust system to allow an amount of air corresponding to a varying amount of fuel in the fuel tank to get in and out of the fuel tank.
In an ordinary air intake/exhaust system, an inside of the fuel tank is connected to the air intake system via a canister and, if a large amount of fuel is fed toward the canister with the fuel tank full of fuel, the canister becomes wet and inoperative. A fuel cutoff apparatus is therefore installed at an upper portion of the fuel tank, functioning to prevent a large amount of fuel vapor from being sent toward the canister when the fuel tank is full.
Japanese Patent Application Laid-Open Publication No. HEI 10-238429, for example, discloses a fuel cutoff apparatus disposed at an upper portion of a fuel tank as a related art to the invention.
The fuel cutoff apparatus disposed at the upper portion of the fuel tank as a related art to the invention will be described with reference to FIG. 1.
There is provided a fuel cutoff apparatus 2 at an upper portion of a fuel tank 1. The fuel cutoff apparatus 2 is of dual construction. A plurality of openings 4 that allow fuel to flow in are provided in a side face of an outer casing 3. In addition, there are provided valve openings 5A, 5B at a top portion of the outer casing 3. The outer casing 3 is secured to a mounting casing 6 which is, in turn, secured to the fuel tank 1. The mounting casing 6 is provided with a port 7 that communicates with a side of the canister (not shown).
An inner float 8 is provided so as to be vertically movable inside the outer casing 3. Valve bodies 9A, 9B that open and close the valve openings 5A, 5B are provided at a top of the inner float 8.
There is provided an exhaust port 10 for exhausting that part of fuel that flows into the outer casing 3 at a bottom end of the outer casing 3 and a hollow valve 11 for opening and closing the exhaust port 10 is also provided. The hollow valve 11 keeps the exhaust port 10 open when the fuel level remains low, but, as the fuel level becomes high, the hollow valve 11 floats up through buoyancy to close the exhaust port 10.
The operation of the fuel cutoff apparatus constructed as described in the foregoing will be explained.
When a fuel level L is low, the inner float 8 is located at a level downward the outer casing 3, which keeps the valve openings 5A, 5B open. The hollow valve 11 is located downward to keep the exhaust port 10 open.
When the fuel level L becomes equivalent to, or higher than, the level of the hollow valve 11, the hollow valve 11 goes up to close the exhaust port 10.
When the fuel level L becomes higher than the level of the openings 4, fuel flows into the outer casing 3 through the openings 4. Since the exhaust port 10 is closed, the fuel that has flown in is stored inside the outer casing 3.
This results in the inner float 8 being raised through buoyancy. At this time, however, the valve body 9B closes only the valve opening 5B and the inner float 8 is yet to close the valve opening 5A. As a result, the fuel level goes even further upward.
When the fuel level goes even further upward, the inner float 8 goes even further upward, in which condition the valve opening 5A is closed by the valve body 9A.
According to the known fuel cutoff apparatus, therefore, fuel can be prevented from being cut off at early stages and, at the same time, the fuel tank can be filled with more fuel to a higher level thereof.
The know fuel cutoff apparatus nonetheless presents the following problems.
Since the hollow valve 11 is provided separately from the inner float 8, the number of parts used increases resulting in an increased cost. The increase in the number of parts used is also disadvantageous in terms of production control.
Referring to FIG. 2, when a fuel cutoff apparatus 21 is mounted on a fuel tank 22, a flow F of fuel sent through a fuel filler pipe 23 makes direct contact with an opening 24 provided in a side of the fuel cutoff apparatus 21. This causes an inner float of the fuel cutoff apparatus 21 to be actuated at early stages, which stops an automatic fuel supplying operation by a filler gun before the fuel tank becomes full, thus requiring additional fuel filling.
It is therefore an object of the invention to provide a fuel cutoff apparatus that prevents an inner float from being actuated at early stages and, at the same time, allows a fuel tank to be topped up regardless of the position at which a fuel filler pipe is mounted.
To achieve the foregoing object, the invention adopts the following embodiments.
A fuel cutoff apparatus according to a first aspect of the invention is provided with an outer casing that is provided with a plurality of openings in a side face thereof and a valve opening in a top thereof, a plate that is provided so as to close a bottom opening of the outer casing and provided with an exhaust port for exhausting fuel, and an inner float that is disposed so as to be vertically movable in an inside of the outer casing and provided with a valve body to open and close the valve opening on a top thereof and a closing portion to close the exhaust port on a bottom thereof.
A fuel cutoff apparatus according to a second aspect of the invention is provided with an outer casing that is provided with a plurality of openings in a side face thereof and a valve opening in a top thereof, an inner float that is provided with a valve body to open and close the valve opening on a top thereof and disposed so as to be vertically movable in an inside of the outer casing, and a cover that covers the openings in the outer casing.
A fuel cutoff apparatus according to a third aspect of the invention is provided with an outer casing and an inner float that is disposed so as to be vertically movable inside the outer casing. The outer casing is provided with a plurality of openings in a side face thereof, an upper hole in an upper portion of the side face thereof, and a valve opening in an upper portion thereof. In addition, a portion formed in a manner to open outwardly is provided at a position lower than the upper hole portion of the outer casing. A valve body that opens and closes the valve opening in the outer casing is provided at an upper portion of the inner float. There is also provided a cover that covers the openings portion in the outer casing.
A fuel cutoff apparatus according to a fourth aspect of the invention is provided with an outer casing and an inner float that is disposed so as to be vertically movable inside the outer casing. The outer casing is provided with a plurality of openings in a side face thereof. There is provided an upper hole in an upper portion of the side face of the outer casing and there is a valve opening in a top of the outer casing. There is also provided at an upper portion of the inner float a valve body that opens and closes the valve opening in the outer casing. In addition, the fuel cutoff apparatus according to the fourth aspect of the invention is provided a cover that covers the upper hole portion of the outer casing and the openings portion of the outer casing. Moreover, there is provided in an intermediary portion of the cover between the upper hole portion and the openings a slope surface of a recessed portion formed by narrowing the diameter. There is also at a top end of the cover a portion with a diameter larger than a main body of the cover formed in a manner to open outwardly.
A fuel cutoff apparatus according to a fifth aspect of the invention is provided with an outer casing and an inner float that is disposed so as to be vertically movable inside the outer casing. The outer casing is provided with a plurality of openings in a side face thereof. There is provided an upper hole in an upper portion of the side face of the outer casing and there is a valve opening in a top of the outer casing. There is also provided at an upper portion of the inner float a valve body that opens and closes the valve opening in the outer casing. In addition, the fuel cutoff apparatus according to the fifth aspect of the invention is provided a first cover of a shape of a skirt that covers the upper hole portion of the outer casing and a second cover that covers the openings portion of the outer casing.
A fuel cutoff apparatus according to a sixth aspect of the invention is provided with an outer casing and an inner float that is disposed so as to be vertically movable inside the outer casing. A valve opening is provided on a top of the outer casing. There is provided at a top of the inner float a valve body that opens and closes the valve opening in the outer casing. The outer casing is of a multiple-diameter structure. An opening comprising a vertical hole is provided at a portion with an enlarging diameter. In addition, an upper hole comprising a vertical hole is provided at another portion with an enlarging diameter located higher than the portion with an enlarging diameter having the opening therein.
The following effects can be derived from the invention described in the foregoing discussion.
According to each of the aspects of the invention, the fuel cutoff apparatus can be prevented from being actuated at early stages. In addition, the number of parts used can be decreased for the reduced cost as well as the enhanced ease of assembly. The degree of freedom in installation of the fuel cutoff apparatus can also be enhanced because of the connection with the mounting position of the filler pipe.